/*
	This file is part of cpp-ethereum.
	cpp-ethereum is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.
	cpp-ethereum is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.
	You should have received a copy of the GNU General Public License
	along with cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
/** @file FixedHash.h
 * @author Gav Wood <i@gavwood.com>
 * @date 2014
 *
 * The FixedHash fixed-size "hash" container type.
 */

#ifndef __FIXEDHASH_H__
#define __FIXEDHASH_H__

#include <algorithm>
#include <array>
#include <cstdint>
#include <random>

#include <boost/functional/hash.hpp>

#include "CommonData.h"

namespace dev
{

    /// Compile-time calculation of Log2 of constant values.
    template <unsigned N> struct StaticLog2 { enum { result = 1 + StaticLog2<N/2>::result }; };
    template <> struct StaticLog2<1> { enum { result = 0 }; };

    extern std::random_device s_fixedHashEngine;

    /// Fixed-size raw-byte array container type, with an API optimised for storing hashes.
    /// Transparently converts to/from the corresponding arithmetic type; this will
    /// assume the data contained in the hash is big-endian.
    template <unsigned N>
    class FixedHash
    {
    public:
        /// The corresponding arithmetic type.
        using Arith = boost::multiprecision::number<boost::multiprecision::cpp_int_backend<N * 8, N * 8, boost::multiprecision::unsigned_magnitude, boost::multiprecision::unchecked, void>>;

        /// The size of the container.
        enum { size = N };

        /// A dummy flag to avoid accidental construction from pointer.
        enum ConstructFromPointerType { ConstructFromPointer };

        /// Method to convert from a string.
        enum ConstructFromStringType { FromHex, FromBinary };

        /// Method to convert from a string.
        enum ConstructFromHashType { AlignLeft, AlignRight, FailIfDifferent };

        /// Construct an empty hash.
        FixedHash() { m_data.fill(0); }

        /// Construct from another hash, filling with zeroes or cropping as necessary.
        template <unsigned M> explicit FixedHash(FixedHash<M> const& _h, ConstructFromHashType _t = AlignLeft) 
        { 
            m_data.fill(0); 
            unsigned c = std::min(M, N); 
            for (unsigned i = 0; i < c; ++i) 
            {
                m_data[_t == AlignRight ? N - 1 - i : i] = _h[_t == AlignRight ? M - 1 - i : i]; 
            }
        }

        /// Convert from the corresponding arithmetic type.
        FixedHash(Arith const& _arith) { toBigEndian(_arith, m_data); }

        /// Convert from unsigned
        explicit FixedHash(unsigned _u) { toBigEndian(_u, m_data); }

        /// Explicitly construct, copying from a byte array.
        explicit FixedHash(bytes const& _b, ConstructFromHashType _t = FailIfDifferent) 
        { 
            if (_b.size() == N)
            { 
                memcpy(m_data.data(), _b.data(), std::min<unsigned>(_b.size(), N)); 
            }
            else 
            { 
                m_data.fill(0); 
                if (_t != FailIfDifferent) 
                { 
                    auto c = std::min<unsigned>(_b.size(), N); 
                    for (unsigned i = 0; i < c; ++i) 
                    {
                        m_data[_t == AlignRight ? N - 1 - i : i] = _b[_t == AlignRight ? _b.size() - 1 - i : i]; 
                    }
                } 
            } 
        }

        /// Explicitly construct, copying from a byte array.
        explicit FixedHash(bytesConstRef _b, ConstructFromHashType _t = FailIfDifferent) { if (_b.size() == N) memcpy(m_data.data(), _b.data(), std::min<unsigned>(_b.size(), N)); else { m_data.fill(0); if (_t != FailIfDifferent) { auto c = std::min<unsigned>(_b.size(), N); for (unsigned i = 0; i < c; ++i) m_data[_t == AlignRight ? N - 1 - i : i] = _b[_t == AlignRight ? _b.size() - 1 - i : i]; } } }

        /// Explicitly construct, copying from a bytes in memory with given pointer.
        explicit FixedHash(byte const* _bs, ConstructFromPointerType) { memcpy(m_data.data(), _bs, N); }

        /// Explicitly construct, copying from a  string.
        explicit FixedHash(std::string const& _s, ConstructFromStringType _t = FromHex, ConstructFromHashType _ht = FailIfDifferent): FixedHash(_t == FromHex ? fromHex(_s, WhenError::Throw) : dev::asBytes(_s), _ht) {}

        /// Convert to arithmetic type.
        operator Arith() const { return fromBigEndian<Arith>(m_data); }

        /// @returns true iff this is the empty hash.
        explicit operator bool() const { return std::any_of(m_data.begin(), m_data.end(), [](byte _b) { return _b != 0; }); }

        // The obvious comparison operators.
        bool operator==(FixedHash const& _c) const { return m_data == _c.m_data; }
        bool operator!=(FixedHash const& _c) const { return m_data != _c.m_data; }
        bool operator<(FixedHash const& _c) const { for (unsigned i = 0; i < N; ++i) if (m_data[i] < _c.m_data[i]) return true; else if (m_data[i] > _c.m_data[i]) return false; return false; }
        bool operator>=(FixedHash const& _c) const { return !operator<(_c); }
        bool operator<=(FixedHash const& _c) const { return operator==(_c) || operator<(_c); }
        bool operator>(FixedHash const& _c) const { return !operator<=(_c); }

        // The obvious binary operators.
        FixedHash& operator^=(FixedHash const& _c) { for (unsigned i = 0; i < N; ++i) m_data[i] ^= _c.m_data[i]; return *this; }
        FixedHash operator^(FixedHash const& _c) const { return FixedHash(*this) ^= _c; }
        FixedHash& operator|=(FixedHash const& _c) { for (unsigned i = 0; i < N; ++i) m_data[i] |= _c.m_data[i]; return *this; }
        FixedHash operator|(FixedHash const& _c) const { return FixedHash(*this) |= _c; }
        FixedHash& operator&=(FixedHash const& _c) { for (unsigned i = 0; i < N; ++i) m_data[i] &= _c.m_data[i]; return *this; }
        FixedHash operator&(FixedHash const& _c) const { return FixedHash(*this) &= _c; }
        FixedHash operator~() const { FixedHash ret; for (unsigned i = 0; i < N; ++i) ret[i] = ~m_data[i]; return ret; }

        // Big-endian increment.
        FixedHash& operator++() { for (unsigned i = size; i > 0 && !++m_data[--i]; ) {} return *this; }

        /// @returns true if all one-bits in @a _c are set in this object.
        bool contains(FixedHash const& _c) const { return (*this & _c) == _c; }

        /// @returns a particular byte from the hash.
        byte& operator[](unsigned _i) { return m_data[_i]; }
        /// @returns a particular byte from the hash.
        byte operator[](unsigned _i) const { return m_data[_i]; }

        /// @returns an abridged version of the hash as a user-readable hex string.
        std::string abridged() const { return toHex(ref().cropped(0, 4)) + "\342\200\246"; }

        /// @returns a version of the hash as a user-readable hex string that leaves out the middle part.
        std::string abridgedMiddle() const { return toHex(ref().cropped(0, 4)) + "\342\200\246" + toHex(ref().cropped(N - 4)); }

        /// @returns the hash as a user-readable hex string.
        std::string hex() const { return toHex(ref()); }

        /// @returns a mutable byte vector_ref to the object's data.
        bytesRef ref() { return bytesRef(m_data.data(), N); }

        /// @returns a constant byte vector_ref to the object's data.
        bytesConstRef ref() const { return bytesConstRef(m_data.data(), N); }

        /// @returns a mutable byte pointer to the object's data.
        byte* data() { return m_data.data(); }

        /// @returns a constant byte pointer to the object's data.
        byte const* data() const { return m_data.data(); }

        /// @returns begin iterator.
        auto begin() const -> typename std::array<byte, N>::const_iterator { return m_data.begin(); }

        /// @returns end iterator.
        auto end() const -> typename std::array<byte, N>::const_iterator { return m_data.end(); }

        /// @returns a copy of the object's data as a byte vector.
        bytes asBytes() const { return bytes(data(), data() + N); }

        /// @returns a mutable reference to the object's data as an STL array.
        std::array<byte, N>& asArray() { return m_data; }

        /// @returns a constant reference to the object's data as an STL array.
        std::array<byte, N> const& asArray() const { return m_data; }

        /// Populate with random data.
        template <class Engine>
        void randomize(Engine& _eng)
        {
            for (auto& i: m_data)
                i = (uint8_t)std::uniform_int_distribution<uint16_t>(0, 255)(_eng);
        }

        /// @returns a random valued object.
        static FixedHash random() { FixedHash ret; ret.randomize(s_fixedHashEngine); return ret; }

        struct hash
        {
            /// Make a hash of the object's data.
            size_t operator()(FixedHash const& _value) const 
            { 
                return boost::hash_range(_value.m_data.cbegin(), _value.m_data.cend()); 
            }
        };

        template <unsigned P, unsigned M> inline FixedHash& shiftBloom(FixedHash<M> const& _h)
        {
            return (*this |= _h.template bloomPart<P, N>());
        }

        template <unsigned P, unsigned M> inline bool containsBloom(FixedHash<M> const& _h)
        {
            return contains(_h.template bloomPart<P, N>());
        }

        template <unsigned P, unsigned M> inline FixedHash<M> bloomPart() const
        {
            unsigned const c_bloomBits = M * 8;
            unsigned const c_mask = c_bloomBits - 1;
            unsigned const c_bloomBytes = (StaticLog2<c_bloomBits>::result + 7) / 8;
            if((M & (M - 1)) != 0)
            {
                LOG_GENERAL(FATAL,
                            "assertion failed (" << __FILE__ << ":" << __LINE__ << ": "
                                                 << __FUNCTION__ << ")" << " M must be power-of-two");
            }

            if(P * c_bloomBytes > N)
            {
                LOG_GENERAL(FATAL,
                            "assertion failed (" << __FILE__ << ":" << __LINE__ << ": "
                                                 << __FUNCTION__ << ")" << " out of range");
            }
            FixedHash<M> ret;
            byte const* p = data();
            for (unsigned i = 0; i < P; ++i)
            {
                unsigned index = 0;
                for (unsigned j = 0; j < c_bloomBytes; ++j, ++p)
                    index = (index << 8) | *p;
                index &= c_mask;
                ret[M - 1 - index / 8] |= (1 << (index % 8));
            }
            return ret;
        }

        /// Returns the index of the first bit set to one, or size() * 8 if no bits are set.
        inline unsigned firstBitSet() const
        {
            unsigned ret = 0;
            for (auto d: m_data)
                if (d)
                    for (;; ++ret, d <<= 1)
                        if (d & 0x80)
                            return ret;
                        else {}
                else
                    ret += 8;
            return ret;
        }

        void clear() { m_data.fill(0); }

        // needed by using boost_multi_index hash_ordered
        friend size_t hash_value(const FixedHash& h)
        {
            return boost::hash_range(h.m_data.cbegin(), h.m_data.cend());
        }

    private:
        std::array<byte, N> m_data;		///< The binary data.
    };

    template <unsigned T>
    class SecureFixedHash: private FixedHash<T>
    {
    public:
        using ConstructFromHashType = typename FixedHash<T>::ConstructFromHashType;
        using ConstructFromStringType = typename FixedHash<T>::ConstructFromStringType;
        using ConstructFromPointerType = typename FixedHash<T>::ConstructFromPointerType;
        SecureFixedHash() = default;
        explicit SecureFixedHash(bytes const& _b, ConstructFromHashType _t = FixedHash<T>::FailIfDifferent): FixedHash<T>(_b, _t) {}
        explicit SecureFixedHash(bytesConstRef _b, ConstructFromHashType _t = FixedHash<T>::FailIfDifferent): FixedHash<T>(_b, _t) {}
        explicit SecureFixedHash(bytesSec const& _b, ConstructFromHashType _t = FixedHash<T>::FailIfDifferent): FixedHash<T>(_b.ref(), _t) {}
        template <unsigned M> explicit SecureFixedHash(FixedHash<M> const& _h, ConstructFromHashType _t = FixedHash<T>::AlignLeft): FixedHash<T>(_h, _t) {}
        template <unsigned M> explicit SecureFixedHash(SecureFixedHash<M> const& _h, ConstructFromHashType _t = FixedHash<T>::AlignLeft): FixedHash<T>(_h.makeInsecure(), _t) {}
        explicit SecureFixedHash(std::string const& _s, ConstructFromStringType _t = FixedHash<T>::FromHex, ConstructFromHashType _ht = FixedHash<T>::FailIfDifferent): FixedHash<T>(_s, _t, _ht) {}
        explicit SecureFixedHash(bytes const* _d, ConstructFromPointerType _t): FixedHash<T>(_d, _t) {}
        ~SecureFixedHash() { ref().cleanse(); }

        SecureFixedHash<T>& operator=(SecureFixedHash<T> const& _c)
        {
            if (&_c == this)
                return *this;
            ref().cleanse();
            FixedHash<T>::operator=(static_cast<FixedHash<T> const&>(_c));
            return *this;
        }

        using FixedHash<T>::size;

        bytesSec asBytesSec() const { return bytesSec(ref()); }

        FixedHash<T> const& makeInsecure() const { return static_cast<FixedHash<T> const&>(*this); }
        FixedHash<T>& writable() { clear(); return static_cast<FixedHash<T>&>(*this); }

        using FixedHash<T>::operator bool;

        // The obvious comparison operators.
        bool operator==(SecureFixedHash const& _c) const { return static_cast<FixedHash<T> const&>(*this).operator==(static_cast<FixedHash<T> const&>(_c)); }
        bool operator!=(SecureFixedHash const& _c) const { return static_cast<FixedHash<T> const&>(*this).operator!=(static_cast<FixedHash<T> const&>(_c)); }
        bool operator<(SecureFixedHash const& _c) const { return static_cast<FixedHash<T> const&>(*this).operator<(static_cast<FixedHash<T> const&>(_c)); }
        bool operator>=(SecureFixedHash const& _c) const { return static_cast<FixedHash<T> const&>(*this).operator>=(static_cast<FixedHash<T> const&>(_c)); }
        bool operator<=(SecureFixedHash const& _c) const { return static_cast<FixedHash<T> const&>(*this).operator<=(static_cast<FixedHash<T> const&>(_c)); }
        bool operator>(SecureFixedHash const& _c) const { return static_cast<FixedHash<T> const&>(*this).operator>(static_cast<FixedHash<T> const&>(_c)); }

        using FixedHash<T>::operator==;
        using FixedHash<T>::operator!=;
        using FixedHash<T>::operator<;
        using FixedHash<T>::operator>=;
        using FixedHash<T>::operator<=;
        using FixedHash<T>::operator>;

        // The obvious binary operators.
        SecureFixedHash& operator^=(FixedHash<T> const& _c) { static_cast<FixedHash<T>&>(*this).operator^=(_c); return *this; }
        SecureFixedHash operator^(FixedHash<T> const& _c) const { return SecureFixedHash(*this) ^= _c; }
        SecureFixedHash& operator|=(FixedHash<T> const& _c) { static_cast<FixedHash<T>&>(*this).operator^=(_c); return *this; }
        SecureFixedHash operator|(FixedHash<T> const& _c) const { return SecureFixedHash(*this) |= _c; }
        SecureFixedHash& operator&=(FixedHash<T> const& _c) { static_cast<FixedHash<T>&>(*this).operator^=(_c); return *this; }
        SecureFixedHash operator&(FixedHash<T> const& _c) const { return SecureFixedHash(*this) &= _c; }

        SecureFixedHash& operator^=(SecureFixedHash const& _c) { static_cast<FixedHash<T>&>(*this).operator^=(static_cast<FixedHash<T> const&>(_c)); return *this; }
        SecureFixedHash operator^(SecureFixedHash const& _c) const { return SecureFixedHash(*this) ^= _c; }
        SecureFixedHash& operator|=(SecureFixedHash const& _c) { static_cast<FixedHash<T>&>(*this).operator^=(static_cast<FixedHash<T> const&>(_c)); return *this; }
        SecureFixedHash operator|(SecureFixedHash const& _c) const { return SecureFixedHash(*this) |= _c; }
        SecureFixedHash& operator&=(SecureFixedHash const& _c) { static_cast<FixedHash<T>&>(*this).operator^=(static_cast<FixedHash<T> const&>(_c)); return *this; }
        SecureFixedHash operator&(SecureFixedHash const& _c) const { return SecureFixedHash(*this) &= _c; }
        SecureFixedHash operator~() const { auto r = ~static_cast<FixedHash<T> const&>(*this); return static_cast<SecureFixedHash const&>(r); }

        using FixedHash<T>::abridged;
        using FixedHash<T>::abridgedMiddle;

        bytesConstRef ref() const { return FixedHash<T>::ref(); }
        byte const* data() const { return FixedHash<T>::data(); }

        static SecureFixedHash<T> random() { SecureFixedHash<T> ret; ret.randomize(s_fixedHashEngine); return ret; }
        using FixedHash<T>::firstBitSet;

        void clear() { ref().cleanse(); }
    };

    /// Fast equality operator for h256.
    template<> inline bool FixedHash<32>::operator==(FixedHash<32> const& _other) const
    {
        const uint64_t* hash1 = (const uint64_t*)data();
        const uint64_t* hash2 = (const uint64_t*)_other.data();
        return (hash1[0] == hash2[0]) && (hash1[1] == hash2[1]) && (hash1[2] == hash2[2]) && (hash1[3] == hash2[3]);
    }

    /// Fast std::hash compatible hash function object for h256.
    template<> inline size_t FixedHash<32>::hash::operator()(FixedHash<32> const& value) const
    {
        uint64_t const* data = reinterpret_cast<uint64_t const*>(value.data());
        return boost::hash_range(data, data + 4);
    }

    /// Stream I/O for the FixedHash class.
    template <unsigned N>
    inline std::ostream& operator<<(std::ostream& _out, FixedHash<N> const& _h)
    {
        _out << toHex(_h);
        return _out;
    }

    /// Stream I/O for the SecureFixedHash class.
    template <unsigned N>
    inline std::ostream& operator<<(std::ostream& _out, SecureFixedHash<N> const& _h)
    {
        _out << "SecureFixedHash#" << std::hex << typename FixedHash<N>::hash()(_h.makeInsecure()) << std::dec;
        return _out;
    }

    // Common types of FixedHash.
    using h2048 = FixedHash<256>;
    using h1024 = FixedHash<128>;
    using h520 = FixedHash<65>;
    using h512 = FixedHash<64>;
    using h256 = FixedHash<32>;
    using h160 = FixedHash<20>;
    using h128 = FixedHash<16>;
    using h64 = FixedHash<8>;
    using h512s = std::vector<h512>;
    using h256s = std::vector<h256>;
    using h160s = std::vector<h160>;
    using h256Set = std::set<h256>;
    using h160Set = std::set<h160>;
    using h256Hash = std::unordered_set<h256>;
    using h160Hash = std::unordered_set<h160>;

    /// Convert the given value into h160 (160-bit unsigned integer) using the right 20 bytes.
    inline h160 right160(h256 const& _t)
    {
        h160 ret;
        memcpy(ret.data(), _t.data() + 12, 20);
        return ret;
    }

    h128 fromUUID(std::string const& _uuid);

    std::string toUUID(h128 const& _uuid);

    inline std::string toString(h256s const& _bs)
    {
        std::ostringstream out;
        out << "[ ";
        for (h256 const& i: _bs)
            out << i.abridged() << ", ";
        out << "]";
        return out.str();
    }
}

namespace std
{
    /// Forward std::hash<dev::FixedHash> to dev::FixedHash::hash.
    template<> struct hash<dev::h64>: dev::h64::hash {};
    template<> struct hash<dev::h128>: dev::h128::hash {};
    template<> struct hash<dev::h160>: dev::h160::hash {};
    template<> struct hash<dev::h256>: dev::h256::hash {};
    template<> struct hash<dev::h512>: dev::h512::hash {};
}

#endif // __FIXEDHASH_H__
